A safety belt apparatus of this kind is known for example from GB 2 131 279. Its principle is based on the fact that an acceleration sensor which is equipped with a sphere as a movable mass has a pawl which is pivotal about a transverse axis and which engages into a tooth at the periphery of a position control ratchet wheel in horizontal movements of the sphere as a result of accelerations or decelerations, through which the position control ratchet wheel, which is connected in a rotationally fixed manner via a transmission to the belt roller, is abruptly braked. Since the belt is drawn further out, the transmission, which is provided between the position control ratchet wheel and the main pawl, experiences a moving out of the main pawl in order that the latter engages into the main ratchet crown and thus stops the drawing out movement of the belt.
A problem in acceleration sensors operating in this manner consists in that the movable mass moves back and forth in the free space surrounding it as a result of the vibrations during normal travel, with the auxiliary pawl also being continually pivoted back and forth. In this it strikes again and again at the outer periphery of the position control ratchet wheel, which leads to disagreeable rattling noises.